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author Jeff Muizelaar <jrmuizel@gmail.com>2021-08-11 16:15:11 -0400
committer GitHub <noreply@github.com>2021-08-11 16:15:11 -0400
commit7b359e1939ff642cbb28d8653fbfa2e337debef8 (patch)
treec6cf726f70476da9cf946e87637ad851eb8f01b9
parent6f04b2f2214f72d24d1036a19b3ca3b9baec38ff (diff)
lwriter.cpp: Elaborate the documentation of some of the VIA pins (#8423)
-rw-r--r--src/mame/drivers/lwriter.cpp14
1 files changed, 12 insertions, 2 deletions
diff --git a/src/mame/drivers/lwriter.cpp b/src/mame/drivers/lwriter.cpp
index 7cdeb199ea5..a19b49f58fa 100644
--- a/src/mame/drivers/lwriter.cpp
+++ b/src/mame/drivers/lwriter.cpp
@@ -378,7 +378,7 @@ void lwriter_state::fifo_out_w(uint8_t data)
* 1 - print sbsy
* 2 - ?
* 3 - ?
- * 4 - some print thing
+ * 4 - print vsreq
* 5 - switch setting low
* 6 - switch setting high
* 7 - print (STATUS/COMMAND Message Line)
@@ -411,13 +411,23 @@ WRITE_LINE_MEMBER(lwriter_state::via_ca2_w)
logerror(" VIA: CA2 written with %d!\n", state);
}
+/* via port b bits:
+ * 0 - ?
+ * 1 - print rdy
+ * 2 - print pprdy
+ * 3 - overlay
+ * 4 -
+ * 5 -
+ * 6 - timer 2 clk
+ * 7 - print related timing thing
+ */
uint8_t lwriter_state::via_pb_r()
{
logerror(" VIA: Port B read!\n");
return 0xFB;
}
-// The 3rd bit is used for talking with the print controller
+// The 3rd bit (PPRDY) is used for talking with the print controller
// and is inverted on II NT
uint8_t lwriter_state::via_pb_lw2nt_r()
{